Mechanism of metastasis to the spermatic cord and testis from advanced gastric cancer: a case report

BACKGROUND: The spermatic cord and testis are very rare sites for metastasis from gastric cancer. Although several mechanisms have been suggested to explain this unusual metastasis, the actual mechanism remains unclear. We report a case of right spermatic cord and testicular metastasis, review its imaging findings, and suggest a mechanism of tumor spread. CASE PRESENTATION: A 61-year-old man complained of a palpable mass in the right inguinal area. He had been treated with distal gastrectomy with chemotherapy for advanced gastric cancer 5 years ago. Computed tomography, ultrasound, and magnetic resonance imaging showed a mass surrounding the right spermatic cord, involving the right testis. Another mass was observed in the aortocaval space, presumed to be a metastatic lymph node. The imaging features of the right testicular lesion were different than those of the primary testicular cancer. The lesions at both sites showed similar radiologic features of abundant internal necrosis, which is consistent with metastatic lesions. Pathology confirmed metastatic adenocarcinoma. He underwent a series of chemotherapy sessions, and all metastatic masses had partially decreased in size at the 5-month outpatient follow-up. CONCLUSIONS: The imaging features of testicular mass and spermatic cord involvement are important clues for accurate differential diagnosis of metastasis from other primary tumors in patients with a history of stomach cancer. This unusual metastasis can be explained via retrograde tumor spread along the lymphatic channels in terms of concurrent aortocaval lymph node metastasis. A suspicion of metastasis should not be overlooked, even if a patient has undergone curative treatment, including surgery and adjuvant chemotherapy, many years ago.